I've done the "carbon vs alloy" thing, and honestly, I'm sticking with alloy. While the carbon wheels do feel a little different, I never noticed any increase in speed, climbing, etc. The alloy wheels I use are the Roval SLX 24, which are light and nice riding. No more carbon wheels for me. But that's for me and my riding style and ability. If you're a world tour rider, well, your mileage may vary.